Mouse2k4

1987 Rx7 Turbo II

As it says in the title, my car is hard to launch which Im pretty sure is poor condition of the clutch hydraulics as the pedal slaps my foot when releasing it.

at 3500+ rpms it seems to lose all power but makes boost fine and still tries real hard.

The car runs premix, mild streetport, ebay exhaust, deleted A/c and p/s. It looks like someone broke a clip off of one of the secondary injectors so they just wired it to the inside of the socket but I still have a hard time believing thats the problem because they still seem pretty secure. They said the fuel pump was upgraded and the ECU is a Rtek 1.7 I think but they didnt say anything about the injectors.

The Car has a rough start I have to feather the throttle a little then it stays on after a couple seconds. No Cold Start.

Now My first reaction would be to check the tps but I havent had access to a DMM in a couple days was wondering if anyone else had a quick fix to this same problem.

Mouse2k4

This hasnt happened in about a week but I feel like its still relevant.

I gotta record a better one but after 3500 rpms it sounds like its struggling to get higher. This video was in 5th gear but should still have been quicker as I was on about 90% throttle.


Edit: Also Im aware my speedometer doesnt work.

Mouse2k4

I decided to check the injectors too see if they were 550 or over 720cc as I am running an rtek 1.7 and I have a feeling my secondaries are probably still 550 however I cant read the very end of the code on there but if anyone can confirm that this is indeed not the correct injector to be using that would be great. Also I would like to take suggestions as to what I should get for secondaries given these are the incorrect ones. Nothing too crazy just some 720s or so just to make it work right.

Mouse2k4

Also I read on the rtek website that it reprograms the ecu to start the injectors at 3500 rpms instead of 3800 which leads me even more to believe these are the wrong injectors as the problem begins right at 3500 rpms.

RXSpeed16

iTrader: (41)

From the FAQ:
What size injectors does my RX-7 use? What colour are they?
Year Engine Plug Size Colour Part #
84-85 13B NA, low square center, 680cc, orange, 195500-0900
86-87 13B NA, low square center, 460cc, red, 195500-1350
86-87 13B Turbo, low square center, 550cc, tan, 195500-1370
88 13B NA, high square offset, 460cc, purple, 195500-1350
88 13B Turbo, high square offset, 550cc, purple, 195500-1370
89-91 13B NA, high oval center, 460cc, red, 195500-2010
89-91 13B Turbo, high oval center, 550cc, purple, 195500-2020

-Check for where the connector tab is to verify impedence.
-Check for a resistor pack up near the AFM.
-Check label on ECU for rtek or not. They put a software version, serial # on the outside. Or at least on their chips if it was a self-install. Can't tell you if you have the wrong injectors without knowing what the right ones are.
-Check the wiring to the secondary injectors by grounding out the wire at the ecu briefly and listening for a click.

The cutout at 3500 is indicative of a secondary injector issue, so you're on the right track.

Mouse2k4

It is an rtek 1.7 and it is low impedence. The injector has a serial code on it but the numbers are melted off so I cant get the whole serial. The fact that they look so used leads me to believe they've been in the car for 25 years and therefor are not the correct injectors to be running with the rtek 1.7 so Im going to buy some 720cc injectors and see what that does. In theory it should fix my issue.

Mouse2k4

I have a spare stock ecu I was thinking about trying. Anybody think of any reasons as to why this would be a bad idea because im not sure the effects it could have.

Mouse2k4

Still havent decided what I want to do with this. Anybody that can give me some assurance that my hunch of the secondaries being too small is true.

RXSpeed16

iTrader: (41)

The cut-off around 3500 is a pretty sure sign there is a problem with the secondary injectors.
I cannot read the picture either so I can't help in identifying them. I *suspect* they are stock 550cc injectors. You can get them cleaned and flow tested to be sure.

Trying the stock ecu won't be a problem, it will just run rich any time the secondaries are firing. You'll need a wideband to tell just how rich you are. If your AFR's are around low 13's under boost, you've probably got stock injectors.

Check the wiring to the injectors. You can ground out the signal wire at the ecu and listen for a click.

Even if you do find a problem with the wiring, replace your secondaries with 720's before running the rtek 1.7. Running 550's in the secondaries WILL blow your engine.

Mouse2k4

Cool thanks. I dont think Im going to put the spare ecu in because I dont know where its been but Im going to replace the injectors with 720s because logic tells me these are 550 but I've got another question.

I dont think Im getting O/D in 5th gear because the rpms stay high like 2900 and the shift light comes on. Now, the car hasnt had a functional speedometer since I got it. Could this be disabling the O/D because the car doesnt know how fast its going?

Mouse2k4

anybody see any problem with running 720s in the primaries and the secondaries for my current application?

Silverfc88

iTrader: (7)

I don't think you will be able to get it to idle with 720's on the bottom with the rtek 1.7. You will need atleast the 1.8 or higher to run 720's all around.

Mouse2k4

fair enough. I ask because I bought a pack of 4 injectors. so ill probably sell the other 2 and get my 2 spare 550s cleaned. maybe sell em as a package for another rtek 1.7 user

Mouse2k4

The new secondary injectors are in! and instead of struggling at 3500 it seems to rather go much faster. The old injectors I confirmed that they were absolutely stock tII injectors. Serial code 195530-1370. The rear injector was legible.

Ma7daPOW3R

iTrader: (4)

Do you still have the other 2 720s? If so what brand and model number and are they high or low impedance?

Juangvb

What brand?